docs: def create_assets_if_needed(corpus, path, entry):
          """ Create File/Utterance/Issuer, if they not already exist and return utt-idx. """
          file_idx = entry[1]
  
          if file_idx not in corpus.utterances.keys():
              speaker_idx = entry[0]
              transcription = entry[2]
  
              age = CommonVoiceReader.map_age(entry[5])
              gender = CommonVoiceReader.map_gender(entry[6])
  
              file_path = os.path.join(path, 'clips', '{}.wav'.format(file_idx))
  
              corpus.new_file(file_path, file_idx)
  
              if speaker_idx in corpus.issuers.keys():
                  issuer = corpus.issuers[speaker_idx]
              else:
                  issuer = issuers.Speaker(speaker_idx, gender=gender, age_group=age)
                  corpus.import_issuers(issuer)
  
              utterance = corpus.new_utterance(file_idx, file_idx, issuer.idx)
              utterance.set_label_list(
                  annotations.LabelList.create_single(
                      transcription,
                      idx=audiomate.corpus.LL_WORD_TRANSCRIPT
                  )
              )
  
          return file_idx